The villa's secret gardens, majestic terraces, sprawling lawns and statues of Byron, Victor Hugo and Goethe are at risk from the city's cash-making initiatives, the activists say.

"The city council continues to authorize events that are utterly incompatible with the area's historical value," said Lorenzo Parlati, head of the Rome branch of Legambiente, the national environmental group.

Once a must-see on the Grand Tour of Europe, it contains an 18th century artificial lake, dozens of monumental fountains and the Galleria Borghese museum, home to masterpieces by artists such as Bernini, Titian and Raphael.

Earlier this month, tens of thousands of soccer fans watched World Cup matches on big screens in the villa's Piazza di Siena equestrian show grounds and many left a trail of graffiti, beer cans and broken vuvuzelas in their wake.

Activists had urged the city not to grant permission for the venue to be used as one of FIFA's Fan Fest sites but were overruled. They have since launched a media campaign to draw attention to their concern for the park they love.

"The 50,000 high-spirited fans that came to watch the matches each evening not only left behind mounds of rubbish, but also defaced statues," Parlati told Reuters.

The council's decision to allow Italian singer Renato Zero to perfom there next month has prompted several environmental and heritage organizations to warn that they may take legal action against the city.

Legambiente and its sister group Italia Nostra (Our Italy) have told the council that they will present testimonial and photographic evidence of the deterioration of the park to Rome's public prosecutor's office.

Mirella Belvisi of Italia Nostra said Italy's villas and piazzas should not be used willy-nilly as arenas for pop concerts or big-screen events to raise cash in one of the most heavily indebted countries in Europe.

"This is no excuse for exploiting villas and historic piazzas as money-making machines. Villa Borghese in particular has been massacred, reduced to an unrecognizable state of comatose," she told Reuters.

Originally a vineyard before it was converted in 1605 into a private park for the powerful Borghese family, the villa, at 148 acres is even bigger than the Vatican.